Thread comparator



Nov. 21, 1961 v B. w. SWANSON ETAL THREAD COMPARATOR 2 Sheets-Sheet 1 Filed Aug. 14, 1959 FIG. 2.

Nov. 21, 1961 SWANSON ETAL 3,009,253

THREAD COMPARATOR Filed Aug. 14, 1959 2 Sheets-Sheet 2 United States Patent OfiFice 3,0b9,25'3 Patented Nov. 21, 1961 3,009,253 THREAD COMPARATOR Bror W. Swanson, 81 Rumford St., West Hartford,

Conn.; Vincent S. Jamilkowski, 74 Smith Drive, East Hartford, Conn.; and John Grzywna, 12 Lincoln Ave.,

West Hartford, Conn.

Filed Aug. 14, 1959, Ser. No. 833,873 6 Claims. (Cl. 33-199) The present invention relates to gauges generally and in particular to a thread comparator.

Previously proposed and presently in use are devices for comparing the threads on a workpiece with a master or sample piece. Such devices have included gauges for measuring the total diameter of a threaded article, gauges for measuring the threads of the article, and gauges for measuring the diameter of the article at the base of the threads.

An object of the present invention is to provide a thread comparator for gauging, in successive steps, composite pitch diameter and actual pitch diameter.

Another object of the present invention is to provide a thread comparator for gauging a workpiece at an infinite number of diametrically opposed positions in a single operation.

A further object of the present invention is to provide a thread comparator which may be employed to gauge a male screw-threaded portion of a workpiece having a composite diameter consisting of a pitch diameter, lead error, and a flank angle error all included.

A still further object of the present invention is to provide a thread comparator which is adaptable to compare the threads of a workpiece, such as a bolt, Within a wide range of diameters and pitch combinations with ease and facility, and one which employs easily and quickly replaceable anvil supporting means for changing the comparator anvils from one diameter or pitch of thread to another diameter or pitch of thread.

Yet another object of the present invention is to provide a thread comparator which is simple in structure, one sturdy in construction, one economical to manufacture and assemble, and one which is highly eifective in action.

These and other objects and advantages of the present invention will be fully apparent from the following description when taken in conjunction with the annexed drawings, in which:

FIGURE 1 is a side elevational view of the comparator according to the present invention with a portion of the standard broken away;

FIGURE 2 is a view taken on the line 22 of FIG- URE 1;

FIGURE 3 is a front elevational view of the comparator with a portion broken away;

FIGURE 4 is a view taken on the line 44 of FIG- URE 3; I

FIGURE 5 is a view of the face of one of the anvils employed in the comparator;

FIGURE 6 is a side elevational view of one of the anvils;

FIGURE 7 is an end elevational view of one of the anvils;

FIGURE 8 is a view on an enlarged scale, taken on the line 88 of FIGURE 4;

FIGURE 9 is a view on an enlarged scale, taken on the line 9-9 of FIGURE 4;

FIGURE 10 is a fragmentary view in section showing the teeth of one anvil engaging the thread of a workpiece; and

FIGURE 11 is a view similar to FIGURE 10, showing the truncated teeth of the anvil engaging the workpiece thread.

Referring in greater detail to the drawings in which like numerals indicate like parts throughout the several views, the thread comparator of the present invention comprises a standard designated generally by the reference numeral 10 and having a lower face 12 adapted for resting upon a supporting surface.

The forward portion of the standard 10 carries on its upper end an anvil support 14 secured to the standard 10 by means of a cap screw 16 (FIGURE 3). A vertical bore 18 extends through the anvil support 14 (FIGURE 4) and receives therein a positioning pin 20-projecting from the lower face of a lower anvil 22. A set screw 24 releasably secures the positioning pin 20 within the anvil support 14. An alignment pin 26 projects from the lower face of the lower anvil 22 and is received in a bore 28 provided in the upper face of the anvil support 14.

In FIGURE 1, the reference numeral 30 designates generally a carriage carried by the standard 10 for rolling transverse back and forth movement horizontally. As shown in FIGURES 2 and 9, the carriage 30 has a V-shaped notch 32 cut in its upper end and extending from one end to the other end and another V-shaped notch 34 extending from the one end to the other end and cut into the lower end. A plurality of balls 36 arranged in spaced relation in the notches 32 and 34 support the carriage 30 between spaced support members 38 and 40 which are adjustably secured in the upper end portion of the standard 10. The support members 38 and 40 are formed with complementally arranged notches, as at 42, receiving the balls 36.

With reference to FIGURE 2, the lower support member 40 is secured in the standard 10 by means of cap screws 44 and the upper support member 38 is adjustably secured in the standard 10 by means of set screws 46. Other cap screws 48, shown only in section in FIGURE 1, secure the upper support member 38 in any position of its adjusted movement within the standard 10.

One end of the carriage 30 is provided with a bore 50 extending inwardly from that end and terminating at a point spaced from that end. Such end of the carriage 30 bears against a rubber bumper 52 when the carriage is at one limit of its back and forth movements within the standard 10. A piston 54 extends into the bore 50 and serves to restrain free movement of the'carriage 30 back and forth within the standard 10 in the manner of a dashpot.

On the end of the carriage 30 remote from the bore 50 is an upstanding support 56 carrying on its upper end a conventional dial indicator assembly 58.

A head 60 is disposed adjacent to and spaced above the lower anvil 22 and is mounted on the support 56 for resilient upward and downward movement. The carriage 30 constitutes means connecting the head 60 to the standard 10 for transverse back and forth movement with respect to the lower anvil 22.

An upper anvil 62 is disposed below and adjacent the head 60 and is connected to the head for limited lateral movement with respect to the head 60. Specifically, an anvil support 64 is interposed between the upper anvil 62 and the lower face of the head 60 and is detachably secured to the upper anvil 62, the anvil support 64 being connected to the head 60 for limited lateral movement with respect to the head 60. The support 64 is provided with a vertical bore 66 in which is received a pin 68 projecting from the upper face of the upper anvil 62. A set screw 70 detachably secures the pin 68 in the bore 66 and a positioning pin 72 projects upwardly from the upper face of the upper anvil 62 and is received in a complementally shaped bore 74 extending upwardly from the lower face of the anvil support 64.

The head 60 is cut away on its lower face to provide a trackway having V-shaped grooves along the sides thereof, as at 76 in FIGURE 4, in which are balls 7 8 rollably supporting the anvil support. 64 for limited lateral back and forth movement. One wall 80 of the trackway formed in the head 60 is detachably secured thereto by one or more cap screws 82.

The portion of the anvil support 64 received within the trackway formed in the head 60 is of a lesser length than the head 60, as shown in FIGURE 3, and springs 84, only one of which is shown, are supported in bores 85 provided in the anvil support 64 and have their free ends hearing against strap members 86 which depend from the head 60 and extend over the ends of the bores in which the springs 84 are positioned. The springs 84 provide the anvil support 64 with resilient centering of the anvil support 64 with respect to the head 60 and yet permit limited lateral movement of the anvil support 64.

The' head 60 carrying the anvil support 64 and the upper anvil 62 is connected to the carriage 30 for up ward and downward movement and for limited rotational movement. Specifically, the head 60 is provided with a centrally located bore 88 extending vertically therethrough and in which is seated and secured one end of a vertically disposed plunger 90. A bore 92 is provided in the support 56 and the plunger 90 is reciprocably mounted within the bore 92. The support 56 is provided with a counterbore concentrically arranged with respect to the bore 92, as at 94 in FIGURE 4, in which is seated a coil spring96 having one end bearing against the upper face of the head 60. The spring 96 biases the plunger downwardly within the bore 92 and counter bore 94. The rotational movement of the head 60- is resiliently limited in clockwise and counterclockwise directions by a U-shaped spring 33, FIGURES 4 and 9, which has its bight 29 secured by screws 61 to the head 60 and the free ends of its legs 35 and 37 bearing against the adjacent parts of the carriage 30.

The plunger 90 is provided with a bore 98 extending inwardly from the upper end and terminating at a point substantially contiguous to the upper face of the head 60.

Slidably mounted within the bore 98 is a plunger 100 biased for upward movement by a coil spring 102 seated in the closed end of the bore 98. A plug 104 has a central bore which receives the reduced upper end portion 99 of the plunger 100, the plug 104 being threadedly engaged in the enlarged upper end portion of the bore 98. The plunger 100 is provided with a shoulder which abuts the under face of the plug 104, preventing the plunger 100 from leaving the bore 98. The actuating stem 106 of the dial indicator assembly 58 bears against the free end of the reduced diameter portion 99 on the upper end of the plunger 100.

Upon upward movement of the upper anvil 62, the head 60 is carried upwardly and the plunger 90 slides upwardly in the bore 92 to effect the movement of the needle 108 of the assembly 58.

A collar 110 is employed to secure the assembly 58 on the support 56. An operating handle 112 projects horizontally from the support 56 on one side of the latter.

In FIGURES to 7, inclusive, the anvil 22 is shown. Full threads are provided on the anvil face as at 114, truncated threads in the area marked 116, and the rest of the face of the anvil 22 is left plain as at 118. The anvil 62 is identical but with the full teeth area, the truncated teeth area and the plain area reversed.

In use, a threaded workpiece or article 120 (FIGURE 4) is positioned between the anvils 22 and 62 and the carriage 30 is pulled forwardly by the application of a pulling pressure to the handle 112. This will roll the anvil 62 over the article 120, engaging first the full teeth of the areas 114 of the anvils and secondly, the truncated teeth of the areas 116 of the anvils with the thread of the article 120.

As shown in FIGURE 10, with reference to the teeth of the upper anvil 62, it being understood that the complementally shaped teeth of the anvil 22 are similarly engaged at the same time, an error in the pitch of the thread of the article 120 causes the full teeth of the anvil 62 to engage the thread of the article 120 only at a" and at b. This shifts the indicator needle 108 of the indicator to one point on the dial which is observed and noted. Next (FIGURE 11), as the truncated teeth of the areas 116 of the anvils 22 and 62 engage the thread of the article 120, the deviations from the desired pitch diameter of the article 120 will be indicated on the indicator dial. This permits the operator of the comparator to properly engage the article 120 to make sure that it falls within the tolerances prescribed for the particular class of fit of the article 120.

What is claimed is:

1. In a comparator for testing the condition of threads on articles, a standard, a fixed lower anvil on said standard, a carriage rollably supported for transverse backand-forth movement horizontally carried by said standard and spaced above said lower anvil, a head disposed adjacent to and spaced above said lower anvil and connected to said carriage for upward and downward movement and for limited rotational movement, an upper anvil disposed below and adjacent said head and connected to said head for limited lateral movement with respect to said head, and means operatively connected to said head for indicating the upward and downward movements of said head.

2. In a comparator for testing the condition of threads on articles, a standard, a fixed lower anvil on said standard, a carriage rollably supported for transverse backand-forth movement horizontally carried by said standard and spaced above said lower anvil, a head disposed adjacent to and spaced above said lower anvil and connected to said carriage for upward and downward movement and for limited rotational movement, an upper anvil disposed below and adjacent said head and connected to said head for limited lateral movement with respect to said head, means resiliently limiting the rotational movement of said head, and means operatively connected to said head for indicating the upward and downward movement of said head.

3. In a comparator for testing the condition of threads on articles, a standard, a fixed lower anvil on said standard, a carriage rollably supported for transverse ba'ckand-forth movement horizontally carried by said standard and spaced above said lower anvil, a head disposed adjacent to and spaced above said lower anvil and connected to said carriage for upward and downward movement and for limited rotational movement, an upper anvil disposed below and adjacent said head and connected to said head for limited lateral movement with respect to said head, means operatively connected to said head for indicating the upward and downward move ment of said head, and thread-engaging means on the upper face of said lower anvil and on the lower face of said upper anvil for rollably engaging the threads of a workpiece when positioned between said anvils and upon execution of back-and-forth movement of said carriage.

4. In a comparator for testing the condition of threads on articles, a standard, a fixed lower anvil on said standard, a carriage rollably supported for transverse backand-forth movement horizontally carried by said standard and spaced above said lower anvil, an upstanding sup port on said carriage and spaced above said lower anvil, a head interposed between said support and said lower anvil, means connecting said head to said support for upward and downward movement and for limited rotational movement, an upper anvil disposed below and adjacent said head and connected to said head for limited lateral movement with respect to said head, and means operatively connected to said head for indicating the upward and downward movement of said head.

5. In a compartor for testing the condition of threads on articles, a standard, a fixed lower anvil on said standard, a carriage rollably supported for transverse backand-forth movement horizontally carried by said standard and spaced above said lower anvil, an upstanding support onsaid carriage and spaced above said lower anvil, a head interposed between said support and said lower anvil, means embodying a plunger reciprocable and rotatable to a limited degree in said head connecting said head to said support for upward and downward movement and for limited rotational movement, an upper anvil disposed below and adjacent said head and connected to said head for limited lateral movement with respect to said head, and means operatively connected to said plunger for indicating the upward and downward movement of said head.

6. In a comparator according to claim 5 which in- 5 cludes in addition thread-engaging means on the upper face of said lower anvil and on the lower face of said upper anvil for rollably engaging the threads on a workpiece when positioned between said anvils and upon execution of back-and-forth movement of said carriage.

References Cited in the file of this patent UNITED STATES PATENTS 1,303,198 Harris May 6, 1919 1,423,339 Ledell July 18, 1922 2,027,217 Zerkle Jan. 7, 1936 2,597,644 Johnson May 20, 1952 FOREIGN PATENTS 598,358 France Sept. 26, 1925 

